net.sf.saxon.expr

## Class NegateExpression

- java.lang.Object
- - net.sf.saxon.expr.Expression
  - - net.sf.saxon.expr.UnaryExpression
    - - net.sf.saxon.expr.NegateExpression

- All Implemented Interfaces:
    Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

      public class NegateExpression
      extends UnaryExpression

  Negate Expression: implements the unary minus operator. This expression is initially created as an ArithmeticExpression (or in backwards compatibility mode, an ArithmeticExpression10) to take advantage of the type checking code. So we don't need to worry about type checking or argument conversion.
  See Also:
    Serialized Form

- - ### Field Summary

    - ### Fields inherited from class net.sf.saxon.expr.UnaryExpression

      `operand`

    - ### Fields inherited from class net.sf.saxon.expr.Expression

      `EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, INHERITED_CONTEXT, INSPECTION_CONTEXT, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, NAVIGATION_CONTEXT, NODE_VALUE_CONTEXT, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, W3C_CONSUMING, W3C_FREE_RANGING, W3C_GROUP_CONSUMING, W3C_MOTIONLESS, WATCH_METHOD`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `NegateExpression(Expression base)` Create a NegateExpression

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `Expression` | `copy()` Copy an expression.
    `protected String` | `displayOperator(Configuration config)` Give a string representation of the operator for use in diagnostics
    `NumericValue` | `evaluateItem(XPathContext context)` Evaluate the expression.
    `ExpressionCompiler` | `getExpressionCompiler()` Return the compiler of the Negate expression
    `String` | `getExpressionName()` Get a name identifying the kind of expression, in terms meaningful to a user.
    `ItemType` | `getItemType(TypeHierarchy th)` Determine the data type of the expression, if this is known statically
    `boolean` | `isBackwardsCompatible()` Ask whether the expression is to be evaluated in XPath 1.0 compatibility mode
    `void` | `setBackwardsCompatible(boolean compatible)` Set whether the expression is to be evaluated in XPath 1.0 compatibility mode
    `Expression` | `typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)` Type-check the expression.

    - ### Methods inherited from class net.sf.saxon.expr.UnaryExpression

      `computeCardinality, computeSpecialProperties, equals, explain, getBaseExpression, hashCode, iterateSubExpressions, optimize, promote, replaceSubExpression, simplify, toString`

    - ### Methods inherited from class net.sf.saxon.expr.Expression

      `addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getImplementationMethod, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSystemId, getSystemId, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSubExpressionInfo, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### NegateExpression

          public NegateExpression(Expression base)

      Create a NegateExpression
      Parameters:
        `base` - the expression that computes the value whose sign is to be reversed

  - ### Method Detail

    - #### setBackwardsCompatible

          public void setBackwardsCompatible(boolean compatible)

      Set whether the expression is to be evaluated in XPath 1.0 compatibility mode
      Parameters:
        `compatible` - true if XPath 1.0 compatibility mode is enabled

    - #### isBackwardsCompatible

          public boolean isBackwardsCompatible()

      Ask whether the expression is to be evaluated in XPath 1.0 compatibility mode
      Returns:
        true if XPath 1.0 compatibility mode is enabled

    - #### typeCheck

          public Expression typeCheck(ExpressionVisitor visitor,
                             ExpressionVisitor.ContextItemType contextItemType)
                               throws XPathException

      Description copied from class: `UnaryExpression`
      Type-check the expression. Default implementation for unary operators that accept any kind of operand
      Overrides:
        `typeCheck` in class `UnaryExpression`
      Parameters:
        `visitor` - an expression visitor
        `contextItemType` - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to `Type.ITEM_TYPE`
      Returns:
        the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
      Throws:
        `XPathException` - if an error is discovered during this phase (typically a type error)

    - #### getItemType

          public ItemType getItemType(TypeHierarchy th)

      Determine the data type of the expression, if this is known statically
      Overrides:
        `getItemType` in class `UnaryExpression`
      Parameters:
        `th` - the type hierarchy cache
      Returns:
        the item type of the items in the result sequence, insofar as this is known statically.

    - #### evaluateItem

          public NumericValue evaluateItem(XPathContext context)
                                    throws XPathException

      Evaluate the expression.
      Overrides:
        `evaluateItem` in class `Expression`
      Parameters:
        `context` - The context in which the expression is to be evaluated
      Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
      Throws:
        `XPathException` - if any dynamic error occurs evaluating the expression

    - #### getExpressionCompiler

          public ExpressionCompiler getExpressionCompiler()

      Return the compiler of the Negate expression
      Overrides:
        `getExpressionCompiler` in class `Expression`
      Returns:
        the relevant ExpressionCompiler

    - #### copy

          public Expression copy()

      Copy an expression. This makes a deep copy.
      Specified by:
        `copy` in class `Expression`
      Returns:
        the copy of the original expression

    - #### displayOperator

          protected String displayOperator(Configuration config)

      Description copied from class: `UnaryExpression`
      Give a string representation of the operator for use in diagnostics
      Overrides:
        `displayOperator` in class `UnaryExpression`
      Parameters:
        `config` - the Saxon configuration
      Returns:
        the operator, as a string

    - #### getExpressionName

          public String getExpressionName()

      Get a name identifying the kind of expression, in terms meaningful to a user.
      Overrides:
        `getExpressionName` in class `Expression`
      Returns:
        a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

Copyright (c) 2004-2013 Saxonica Limited. All rights reserved.